The invention relates to a method and a device for the continuous production of carbon black with a high fullerene content.
In the following the term fullerenes refers to molecular, chemically homogenous and stable fullerenes. Representatives of this group of fullerenes are C60, C70 or C84. These fullerenes are generally soluble in aromatic solvents. A particularly preferred fullerene is the C60 fullerene.
For the production of carbon black containing fullerenes several methods are known. However, the achievable concentration of fullerenes in the obtained carbon black is so low that a preparation of pure fullerenes is only possible with great expenditures. Due to the resulting high price of pure fullerenes interesting applications in different fields of technology are for economical reasons a priori not conceivable. The U.S. Pat. No. 5,227,038 for example, discloses an apparatus for a laboratory allowing to produce a few grams of fullerenes in a discontinuous way by means of an electric arc between carbon electrodes serving as a raw material. Apart from the fact that the produced amounts are tiny, the concentration of fullerenes C50 in the deposited carbon black is very low and never exceeds 10% of the produced mass. Further, the fullerene C60 is in this method present in a mixture with higher fullerene compounds requiring costly fractionation for an isolation with sufficient purity.
The U.S. Pat. No. 5,304,366 describes a method allowing a certain concentration of the product but using a system for filtering a gas circulation at a high temperature which is difficult to practically perform.
The EP-B1 0 682 561 describes a general method for the production of carbon black with a nanostructure defined by the influence of a gaseous plasma on carbon at high temperatures. In product series obtained in this way fullerenes may at sufficient treatment temperatures be obtained in a continuous technical way.
However, the reaction products resulting from the method according to EP-B1 0 682 561 are very impure and contain apart from carbon which has not been transformed into fullerenes at best 10% fullerene C60 as a mixture with higher fullerenes.
It was therefore the problem of the invention to develop a device and a method allowing to continuously produce carbon black with a high content of fullerenes.